Method of producing a hot-formed aluminum base product

ABSTRACT

WHAT IS DISCLOSED HEREIN IS A METHOD OF PRODUCING A HOT-FORMED ALUMINUM-BASE PRODUCT FROM MOLTEN METAL BY SOLIDIFYING A MOLTEN ALUMINUM-BASE METAL TO OBTAIN A CAST METAL, INITIATING THE HOT-FORMING OF THE CAST METAL WHILE THE CAST METAL IS IN SUBSTANTIALLY THAT CONDITION IN WHICH IT SOLIDIFIED, AND NOT-FORMING THE CAST METAL BY DEFORMING THE CAST METAL A SUBSTANTIAL NUMBER OF TIMES TO CAUSE THE CAST METAL TO ELONGATE AT LEAST BY A FACTOR OF TWENTY ALONG AN AXIS OF ELONGATION AND TO CAUSE SUBSTANTIAL MOVEMENT OF THE CAST METAL ALONG A PLURALITY OF AXES SUBSTANTIALLY PERPENDICULAR TO THE AXIS OF ELONGATION. THE METHOD PRODUCES A HOT-FORMED ALUMINUM-BASE PRODUCT IN WHICH THE AS-CAST GRAIN STRUCTURE OF THE CAST METAL IS SUBSTANTIALLY   COMPLETELY DESTROYED AND THE METHOD IS DISCLOSED AS USING A CONTINUOUS CASTING MACHINE IN WHICH MOLTEN ALUMINUMBASE METAL IS SOLIDIFIED TO OBTAIN A CAST METAL AND A ROLLING MILL TO WHICH THE CAST METAL IS PASSED AT HOT-FORMING TEMPERATURE FROM THE CASTING MACHINE AND WHICH HAS A PLURALITY OF ROLL STANDS WHICH ALTERNATIVELY CHANGE THE TRANSVERSE CROSS-SECTIONAL SHAPE OF THE CAST METAL.

Feb. 9, 1971 o. a. COFER METHOD OF PRODUCING A HOT-FORMED ALUMINUM BASE PRODUCT Original Filed June 28, 1967 INVENTOR.

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W14/2Z {214/ gm 7" ,4 r TOE/V5 v5 United States Patent US. Cl. 29-5275 7 Claims ABSTRACT OF THE DISCLOSURE What is disclosed herein is a method of producing a hot-formed aluminum-base product from molten metal by solidifying a molten aluminum-base metal to obtain a cast metal, initiating the hot-forming of the cast metal while the cast metal is in substantially that condition in which it solidified, and hot-forming the cast metal by deforming the cast metal a substantial number of times to cause the cast metal to elongate at least by a factor of twenty along an axis of elongation and to cause substantial movement of the cast metal along a plurality of axes substantially perpendicular to the axis of elongation. The method produces a hot-formed aluminum-base product in which the as-cast grain structure of the cast metal is substantially completely destroyed and the method is disclosed as using a continuous casting machine in which molten aluminumbase metal is solidified to obtain a cast metal and a rolling mill to which the cast metal is passed at hot-forming temperature from the casting machine and which has a plurality of roll stands which alternatively change the transverse cross-sectional shape of the cast metal.

This application is a continuation of Ser. No. 649,658, filed June 28, 1967.

BACKGROUND 3 OF THE INVENTION (1) Field of the invention This invention relates generally to the production of aluminum-base products and more particularly to a method of producing a hot-formed aluminum-base product such as an aluminum rod from molten metal by solidifying a molten aluminum-base metal to obtain a cast metal and by hot-forming the cast metal in its as-cast condition into a hot-formed aluminum-base product.

(2) Description of the prior art The production of a hot-formed aluminum-base product from molten metal is well known in the prior art. However, a difficulty which has been encountered in the prior art in the production of a hot-formed aluminum-base product from molten metal is that a substantial amount of the as-cast grain structure of the cast metal has remained in the hot-formed aluminum-base product. This, in turn, has frequently limited the usefulness of the hot-formed aluminum-base product for drawing into fine Wire and other uses.

Typical of the apparatus which has been used in the prior art to produce a hot-formed aluminum-base product from molten metal is the apparatus shown in US. Pat. No. 2,710,433. With apparatus such as that shown in this US. patent, a hot-formed aluminum-base product is produced by solidifying a molten aluminum-base metal in a casting machine to obtain a cast metal and by initiating the hot-forming of the cast metal at a hot-forming temperature while the cast metal is in substantially that condition in which it solidified.

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The hot-forming disclosed in US. Pat. No. 2,710,433 or as practiced in the prior art with apparatus similar to that shown in this U.S. patent generally results in the cast metal being elongated along its axis of elongation by at least a factor of thirty. However, it also results in relatively little movement of the cast metal transverse to its axis of elongation and in a large amount of the as-cast grain structure of the cast metal remaining in the hotformed aluminum-base product.

US. Pat. No. 3,315,349 discloses a method of producing a hot-formed copper-base product using apparatus which is different from that disclosed in US Pat. No. 2,710,433 and from other apparatus which has been generally used in the prior art in the production of a hotformed aluminum-base product from molten metal. In the method disclosed in -U.S. Pat. No. 3,315,349 the deforming of the cast metal during hot-forming results in substantial movement of the cast metal transverse to its axis of elongation. However, this US. patent is directed to producing a hot-formed copper-base product and does not provide a method of producing a hot-formed aluminum-base product from molten metal in which the as-cast grain structure of the cast metal is substantially completely destroyed.

This is because it has been found that simply moving an aluminum-base cast metal transverse to its axis of elongation during hot-forming of the cast metal does not provide a hot-formed aluminum-base product in which the as-cast grain structure of the cast metal is substantially destroyed. Thus, the prior art does not provide a method of producing a hot-formed aluminum-base product from molten metal which results in a hot-formed aluminumbase product in which the as-cast grain structure of the cast metal is substantially completely destroyed.

SUMMARY OF THE INVENTION The method of producing a hot-formed aluminum-base product from molten metal disclosed herein differs from the prior art in that it provides a hot-formed aluminumbase product in which the as-cast grain structure of the cast metal is substantially completely destroyed. Thus, the method disclosed herein provides a hot-formed aluminumbase product which is well suited to drawing into fine wire or other uses.

The method of producing a hot-formed aluminum-base product from molten metal disclosed herein provides a hot-formed aluminum-base product in which the as-cast grain structure of the cast metal is substantially completely destroyed because it has been found that the as-cast grain structure of the cast metal is substantially completely destroyed if the cast metal is hot-formed in the manner taught in US. Pat. No. 3,315,349 and if in addition, the cast metal is elongated along its axis of elongation by a factor of at least twenty. Thus, the method of producing a hot-formed aluminum-base product from molten metal disclosed herein is a method involving solidifying a molten aluminum-base metal to obtain a cast metal, initiating the hot-forming of the cast metal while the cast metal is in substantially that condition in which it solidified, and hot-forming the cast metal by deforming the cast metal a substantial number of times to cause an elongation of the cast metal along its axis of elongation by a factor of at least twenty and to cause substantial movement of the cast metal along a plurality of axes substantially perpendicular to the axis of elongation.

BRIEF DESCRIPTION OF THE DRAWING These and other features and advantages of the invention will be more clearly understood from the following description and the accompanying drawing in which like characters of reference designate corresponding parts throughout and in which:

FIG. 1 schematically shows one example of apparatus suitable to practice an embodiment of the invention, this apparatus comprising a casting machine and a rolling mill having a plurality of roll stands;

FIG. 2 shows the transverse cross-sectional shapes into which an aluminum-base cast bar is deformed during hotforming in accordance with a first embodiment of the invention;

FIG. 3 shows the transverse cross-sectional shapes into which an aluminum-base cast bar is deformed during hotforming in accordance with a second embodiment of the invention;

FIG. 4 shows the transverse cross-sectional shapes into which an aluminum-base cast bar is deformed during hotforming in accordance with the prior art;

FIG. 5 is a schematic representation of the grain structure in a transverse cross-sectional surface of a cast bar subsequent to solidification from a molten aluminumbase metal but prior to hot-forming;

FIG. 6 is a schematic representation of the grain structure in a transverse cross-sectional surface of an aluminum rod which has been hot-formed from the cast bar of FIG. 5 with elongation of the cast bar along an axis of elongation by a factor of over thirty and without substantial movement of cast metal along axes substantially perpendicular to the axis of elongation of the cast bar;

FIG. 7 is a schematic representation of the grain structure in a transverse cross-sectional surface of an aluminum rod which has been hot-formed from the cast bar of FIG. 5 with elongation of the cast bar along an axis of elongation by a factor of less than twenty and with substantial movement of cast metal along axes substantially perpendicular to the axis of elongation of the cast bar;

FIG. 8 is a schematic representation of the grain structure in a transverse cross-sectional surface of an aluminum rod produced in accordance with the invention in that it has been hot-formed from the cast bar of FIG. 5 with elongation of the cast bar along an axis of elongation by a factor of at least twenty and with substantial movement of cast metal along axes substantially perpendicular to the axis of elongation of the cast bar.

DESCRIPTION OF AN EMBODIMENT These figures and the following detailed description disclose a specific embodiment of the invention. However, it will be understood that the invention is not limited to the details disclosed since it may be embodied in other equivalent forms without departing from the inventive concept.

The method of producing a hot-formed aluminum-base product from molten metal which is disclosed herein is best understood in terms of means suitable to its practice such as the apparatus schematically shown in FIG. 1. This apparatus comprises a continuous casting machine and a rolling mill 11. The continuous casting machine 10 serves as a casting means for solidifying molten metal 9 to provide a cast metal such as a cast bar 12 that is conveyed in substantially that condition in which it solidified from the continuous casting machine 10 to the rolling mill 11 which serves as a hot-forming means for hot-forming the cast bar \12 into aluminum rod 16 or another hot-formed aluminum-base product in accordance with the method which is described below.

The continuous casting machine 10 is of conventional casting wheel type similar to that shown in U.S. Pat. No. 3,318,367 and has a casting wheel 13- with a casting groove (not shown) partially closed by an endless band 14 which is supported against the casting wheel 13 by a plurality of idler wheels 15. The casting wheel 13 and endless band 14 cooperate to provide a mold (not shown) into one end of which molten metal 9 is poured to solidify and from the other end of which the cast bar 12 passes in substantially that condition in which it solidified.

The rolling mill 11 is of conventional type having a plurality of roll stands 17 arranged to hot-form the cast metal by a series of successive deformations. The continuous casting machine 1-0 and the rolling mill 11 are positioned relative to each other so that the cast bar 12 enters the rolling mill 11 substantially immediately after solidification so as to be insubstantially that condition in which it solidified and at a hot-forming temperature within the range of temperatures for hot-forming the cast bar 12. No heating of the cast bar 12 is required between the casting machine 10 and the rolling mill 11 but in the event that it is desired to closely control the hot-forming temperature of the cast bar 12, means for adjusting the temperature of the cast bar 12 (not shown) may be placed between the continuous casting machine 10 and the rolling mill 11 without departing from the inventive concept disclosed herein.

It will be understood that with the apparatus of FIG. 1, the cast bar 12 may be of any one of a plurality of lengths determined only by the amount of molten metal 9 solidified and may extend between the continuous casting machine 10 and the rolling mill 11. Thus, the steps of solidifying molten metal to obtain cast metal and of hot-forming the cast metal are generally being performed simultaneously once the apparatus of FIG. I is in operation.

However, in spite of this advantage and others, the apparatus of FIG. 1 is shown only schematically because each component of the apparatus will be readily understood by those skilled in the art and because once the method disclosed herein is understood, it will be apparent to those skilled in the art that a direct chill casting machine or any one of many other known devices may be substituted as a casting means for the continuous casting machine 10 shown in FIG. 1 and that a continuous forging machine or any one of many other known devices may be substituted as a hot-forming means for the rolling mill 11. This is because the invention provides an improved hot-formed aluminum-base product from molten metal with substantially any apparatus which includes a casting means for solidifying a molten aluminum-base metal to provide a cast metal and a hot-forming means for hot-forming the cast metal in substantially that condition in which it solidified in the manner required by the method disclosed herein.

The manner is which the hot-forming means such as the rolling mill 11 must hot-form a cast metal such as the cast bar 12 is best illustrated by reference to FIGS. 2 and 3 which show in dashed line the cross-sectional shapes of the cast bar 12 as it enters successive roll stands 17 and in solid line the cross-sectional shapes of the cast bar 12 as it leaves the successive roll stands 17. The roll passes (not shown) in the roll stands 17 which are required to compress the cast bar 12 into the cross-sectional shapes of FIGS. 2 and 3 will be understood by those skilled in the art. From FIG, 2 it will be seen that as the cast bar 12 is hot-formed into a hot-formed aluminum-base product such as the aluminum rod 16, the cast bar 12 is deformed by compression into a plurality of cross-sectional shapes transverse to its axis of elongation 20 which are alternately substantially flattened and elongated and substantially round.

From FIG. 3 it will be seen that as the cast bar 12 is hot-formed into a hot-formed aluminum-base product such as the aluminum rod 16, the cast bar 12 is deformed by compression into a plurality of cross-sectional shapes transverse to its axis of elongation 20 which are substantially triangular and alternately rotated by degrees about the axis of elongation 20. In addition, the rolling mill 11 is adjusted in conventional manner so that the plurality of deformations progressively reduced the areas of cross-sectional shapes shown in both FIG. 2 and FIG. 3. The progressively smaller areas of the successive crosssectional shapes shown in both FIG. 2 and FIG. 3 are selected to result in an elongation of the cast bar 12 along its axis of elongation 20 through the rolling mill 11 by a factor of at least twenty.

Roll stands 17 of a rolling mill 11 having roll passes (not shown) which will deform the cast bar 12 into a plurality of transverse cross-sectional shapes such as those shown in FIGS. 2 and 3 while also providing for the elongation of the cast bar 12 by a factor of at least twenty will be apparent to those skilled in the art. Moreover, those skilled in the art will understand that hot-forming a cast bar 12 in the manner provided by cross-sectional shapes such as those shown in FIGS. 2 and 3 results in substantial movement of cast metal in the cast bar 12 not only along the axis of elongation 20 of the cast bar 12 but also relative to the axis of elongation along axes substantially perpendicular to the axis of elongation 20, This is because deforming the cast bar 12 into successive crosssectional shapes such as those shown by either FIG. 2 or FIG. 3 requires that at least some of the cast metal in the cast bar 12 be deformed transverse to the axis of elongation 20 so that substantial portions of the cast metal having a cross-sectional shape have been moved outwardly and inwardly relative to the axis of elongation 20 and their positions when the cast metal had a preceding crosssectional shape. It will also be understood that this required movement of cast metal in the cast bar 12 can be accomplished by a plurality of deformations other than those represented by the transverse cross-sectional shapes of FIGS. 2 and 3.

However, regardless of the specific plurality of deformations used to obtain the required elongation of the cast bar 12 along an axis of elongation by a factor of at least twenty and the required movement of cast metal in the cast bar 12 along a plurality of axes substantially perpendicular to the axis of elongation, the resulting elongation and transverse movement in the hot-forming of a cast metal which has been solidified from molten aluminum-base metal in a casting means and passed in substantially its as-cast condition to a hot-forming means serve to cause a three-dimensional spread of the cast metal and a total movement of the cast metal by an amount which provides a hot-formed aluminum-base product in which substantially none of the as-cast grain structure of the cast metal remains and which is for this reason superior to prior art hot-formed aluminum-base products for drawing into fine wire or other uses. That the method of producing a hot-formed aluminum-base product from molten metal which is disclosed herein produces a superior hot-formed aluminum-base product may be best seen from FIGS. 5 through 8.

FIG. 5 is a schematic representation of the grain structure in a transverse cross-sectional surface of a cast bar 12 obtained by solidifying molten aluminum-base metal 9 in the casting machine 10. The molten aluminum-base metal 9 was blended to provide EC grade aluminum and the large columnar grains 31 and grain orientation shown in FIG. 5 are characteristic of the as-cast grain structure of an aluminum-base cast bar 12. FIG. 8 is a schematic representation of the grain structure in a transverse crosssectional surface of an aluminum rod 16 which has been produced in accordance with the invention disclosed herein by deforming the cast bar 12 during hot-forming in the rolling mill 11 so as to cause an elongation by a factor of approximately twenty along an axis of elongation 20 while at the same time causing substantial movement of cast metal along axes substantially perpendicular to the axis of elongation 20.

FIGS. 6 and 7 are schematic representations of the grain structure in transverse cross-sectional surfaces of aluminum rods 16' and 16 respectively which have been produced by a method other than the invention disclosed herein. The aluminum rod 16' shown in FIG. 6 'was hotformed from the cast bar 12 by deforming the cast bar 12 in substantially its as-cast condition in a hot-forming means such as that shown in US. Pat. No. 2,710,433 and into the plurality of transverse cross-sectional shapes shown in FIG. 4. As with FIGS. 2 and 3, FIG. 4 shows in dashed line the transverse cross-sectional shape of the cast bar 12 as it enters each roll stand such as a roll stand 17 and in solid line, the transverse cross-sectional shape of the cast bar 12 as it leaves each roll stand such as a roll stand 17 .The transverse cross-sectional shapes shown in FIG. 4 were selected in conventional manner by use of appropriate roll passes to cause an elongation along an axis of elongation 20 by a factor of approximately thirty. However, it will be understood that the transverse cross-sectional shapes shown in FIG. 4 do not cause substantial movement of cast metal along a plurality of axes substantially perpendicular to the axis of elongation 20 since substantial portions of the cast metal having a cross-sectional shape have not been moved outwardly relative to the axis of elongation 20 and their positions when the cast metal had a preceding cross-sectional shape. The aluminum rod 16" shown in FIG. 7 was hot-formed from the cast bar 12 by deforming the cast bar 12 into a plurality of transverse cross-sectional shapes similar to those shown in FIGS. 2 and 3 but with the plurality of deformations being selected to elongate the cast bar 12 only by a factor of approximately fifteen.

A comparison of FIG. 5 showing the grain structure of the cast bar 12 prior to hot-forming with FIG. 8 showiny the grain structure of the aluminum rod 16 produced in accordance with the invention serves to show that in the aluminum rod 16, the as-cast grain structure of the cast metal 12 has been substantially completely destroyed. A comparison of FIG. 5 with FIG. 6 showing the grain structure of the aluminum rod 16 serves to show that the as-cast grain structure of the cast bar 12 is still present to a significant degree in an aluminum rod 16' that has been hot-formed to cause elongation of the cast bar 12 along an axis of elongation 20 by a factor of at least twenty 'but not to cause substantial movement of cast metal in the cast bar 12 along axes substantially perpendicular to the axis of elongation 20.

Similarly, a comparison of FIGS. 5 with FIG. 7 showing the grain structure of the aluminum rod 16" serves to show that the as-cast grain structure of the cast bar 12 is still present to a significant degree in an aluminum rod 16 that has been hot-formed to cause an elongation of the cast bar 12 by a factor less than twenty and to cause substantial movement of cast metal in the cast bar 12 along a plurality of axes substantially perpendicular to the axis of elongation. In connection with the aluminum rod 16", it should 'be understood that it has been found that an elongation of the cast bar 12 by a factor of at least twenty is required by the invention and that the aluminum rod 16" is merely representative of a hotformed aluminum-base product which is hot-formed without elongating the cast metal by a factor of at least twenty.

Thus, it will now be understood from FIGS. 5 through 8 that a hot-formed aluminum-base product such as the aluminum rod 16 in which the as-cast grain structure of the cast metal is substantially completely destroyed can be produced from molten metal only by a method which includes solidifying a molten aluminum-base metal to obtain a cast metal and hot-forming the cast metal in its as-cast condition so as to cause both an elongation of the cast metal along an axis of elongation by a factor of at least twenty and substantial movement of the cast metal along a plurality of axes substantially perpendicular to the axis of elongation. In the embodiments of the invention disclosed herein, the required hot-forming of the cast metal is achieved by deforming a cast bar 12 into a plurality of substantially flattened and elongated crosssectional shapes alternately with a plurality of substantially round cross-sectional shapes or into a plurality of substantially triangular cross-section which are altelrnately rotated degrees about the axis of elongation 20 and to an extent that results in a reduction in crosssectional area of the cast bar 12 which is sufi'icient for an elongation of the cast bar 12 by a factor of at least twenty.

However, it will be understood that reforming a cast bar 12 or other cast metal into a plurality of substantially flattened and elongated cross-sections having their long axes angularly disposed to each other or into many other cross-sections would with sufficient: total reduction in cross-sectional area of the cast metal also provide that elongation of the cast metal along an axis of elongation and that movement of the cast metal along axes substantially perpendicular to the axis of elongation during hot-forming which are required by the invention. Thus, it will be understood that variations in the specific crosssectional shapes into which the cast metal is hot-formed and many other variations may be made in the embodiments chosen herein for the purpose of illustrating the present invention without departing from the scope thereof as defined by the appended claims.

I claim:

1. In a method of producing a hot-formed aluminumbase product by solidifying a molten aluminum-base metal to obtain a cast metal and initiating hot-forming of said cast metal while in substantially that condition in which the metal solidified, the step of hot-rolling said cast metal in closed roll passes to deform said cast metal into a plurality of successive alternately different cross-sections which include substantially flattened and elongated crosssections and substantially round cross-sections, and to cause an elongation of said cast metal along an axis of elongation by a factor of at least twenty and to cause substantial movement of cast metal both inwardly and outwardly with respect to the axis of elongation.

2. In a method of producing a hot-formed aluminumbase product by solidifying a molten aluminum-base metal to obtain a cast metal and initiating hot forming of said cast metal while in substantially that condition in which the metal solidified, the step of hot-rolling said cast metal into a plurality of difierent cross-sectional shapes which include a first substantially triangular shape and a second substantially triangular shape rotated 180 about an axis of elongation from said first substantially triangular shape, and to cause an elongation of said cast metal along said axis of elongation by a factor of at least twenty and to cause substantial movement of cast metal both inwardly and outwardly with respect to the axis of elongation.

3. Method of claim 1 wherein said cross-sections are progressively smaller in cross-sectional area.

4. Method of claim 2 wherein said cross-sectional shapes are progressively smaller in cross-sectional area.

5. Method of claim 2 wherein said cast metal is deformed into a plurality of successive alternately different cross-sections which include a first substantially triangular shape and a second substantially triangular shape rotated 180 about an axis of elongation from said first substantially triangular shape.

6. Method of claim 1 wherein the deforming of said cast metal moves said cast metal relative to said axis of elongation by an amount which is sufficient to substantially destroy the as-cast grain structure of said cast metal.

7. Method of claim 2 wherein the deforming of said cast metal moves said cast metal relative to said axis of elongation by an amount which is sufficient to substantially destroy the as-cast grain structure of said cast metal.

References Cited UNITED STATES PATENTS 1,711,000 4/1929 Short 295275 2,710,433 6/1955 Properzi 164270X 3,257,835 6/1966 Cofer et al. 16476X 3,315,349 4/1967 Cofer 16487 3,331,123 7/1967 Cofer 16487X 3,333,624 8/1967 Cofer et al. 16487 3,340,716 9/1967 Funk 29527.7X 3,349,472 1'0/1967 Schlegel 29527.6 3,349,471 10/1967 Bell et al. 16487X 3,450,573 6/1969 Knapton et al. 29527.5X

JOHN F. CAMPBELL, Primary Examiner D. C. REILEY, Assistant Examiner 3, Us. 01. X.R. 16476, 278 

